<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>IE和其他浏览器</title>
</head>
<body>
    <script>
//        解析：因为只有IE浏览器下的对象没有__proto__属性
        console.log("__proto__" in {});

        var a={x:1,y:"b"};
        console.log(a.__proto__);
    </script>
</body>
</html>